86 
to decolorize, and the original colors resulting from the action of the 
tyrosinase, were as follows: 
Number of extract. 
I. 
II. 
III. 
Appearance before titration 
Deep black; black 
sediment. 
Violet black. 
Dark brown. 
Permanganate required c. c 
37.8 
13.6 
8.3 
In order now to determine the effect of hydrogen peroxide on 
each of these extracts, similar experiments were carried out, except 
that to each solution 1 c. c. of 0.05 per cent solution of hydrogen 
peroxide was added to each of the tests. After standing twenty-four 
hours the three solutions were titrated with 0.002 N permanganate, 
with the following results : 
Number of extract. 
I. 
II. 
III. 
Permanganate required c. c 
37.3 
26.7 
23.2 
It is evident from these results that the weaker the tyrosinase the 
greater the accelerating effect of hydrogen peroxide on its activity. 
After a few days extract No. I had become acid in reaction, and was 
slimv and brown and not in a condition to be filtered. In order, 
therefore, to neutralize the acid and coagulate the slimy material, 
the extract was treated with 10 grams of magnesium carbonate and 
filtered. The residue was then treated with 30 c. c. of water, in 
which, however, but little of the residue dissolved. Ten cubic centi- 
meters of this solution were then mixed with an equal volume of the 
tyrosin solution. After twenty-four hours the mixture was entirely 
colorless. When, however, 0.5 c. c. of a 0.05 per cent solution of 
hydrogen peroxide was added, a tolerably rapid oxidation of the 
tvrosin occurred, and in the course of ten hours the mixture was col- 
ored black. It would seem, therefore, that by shaking the extract 
of the fungus with magnesium carbonate the peroxidase of tyrosinase 
can be separated from its oxygenase. A partial separation of the 
constituents of tyrosinase can also be accomplished by means of 
methyl alcohol. Thus, according to Bach (ibid.), 100 c. c. of the 
fungus extract were poured into 500 c. c. of strong methyl alcohol. 
The resulting precipitate was rapidly filtered, washed with methyl 
alcohol, and dried in vacuo over calcium chloride. The dry residue 
was rubbed up in a mortar with 100 c. c. of water, whereby only a 
